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<br />-12- <br /> <br />n. r~O]STURE SOURCES <br />h "11 1?34 <br />T ere are three moisture sources aVdl ab e to the Gore Range. ,-, , <br /> <br />Each of these sources is associated with a different season of the year, <br /> <br />Figure VI-1 illustrates the flow of air &rom these seasonal moisture <br /> <br />';ources, <br /> <br />Winter and spring snows, which form the bulk of the annual precipi- <br /> <br />tation, are a result of moist air maSSES comin9 '"rom the caol Northern <br /> <br />Pacific Ocean in the Gulf of Alaska and inland from the Pacific Northwest. <br /> <br />These air masses must pass over the Cascade Range or the Sierra-Nevada <br /> <br />Range, several ranges 'in Nevada, Idaho and Utah and then a series of <br /> <br />ranges in the Colorado Rockies before arriving at the Gore Range, The <br /> <br />series of uplifts during transit causes Much of the moisture to precipi- <br /> <br />':ate out, thereby limitini) the amount of moisture available for delivery <br /> <br />:0 the Gore Range. However, the passage of these winter storms is <br /> <br />often temporarily slowed during the eastward movement across the continent <br /> <br />due to terrain barriers, thus providing a longer precipitation ti~e. <br /> <br />Summer showers and thunderstorms, w'th moisture pulled in from the <br /> <br />Gulf of Mexico, occur mainly in July and August. This is a result of the <br /> <br />shift in prevailing winds from the southwest to south and southeast <br />caused by the break of the continental winter high pressure cells in the <br /> <br />~;pring. Temperatures 'in the Gore C:"eek Valley aloe still too cald in <br /> <br />dune to provide the uplift necessary to produce significant thunder- <br /> <br />~;torms and the light showers that occur in June only serve to 'increase <br /> <br />the snow pack moisture, The moist air maSS2S for these mid and late <br />